The Parameter Space of Graphene Chemical Vapor Deposition on Polycrystalline Cu

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• 作者：Piran R. Kidambi ; Caterina Ducati ; Bruno Dlubak ; Damian Gardiner ; Robert S. Weatherup ; Marie-Blandine Martin ; Pierre Seneor ; Harry Coles ; Stephan Hofmann
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：October 25, 2012
• 年：2012
• 卷：116
• 期：42
• 页码：22492-22501
• 全文大小：640K
• 年卷期：v.116,no.42(October 25, 2012)
• ISSN：1932-7455

文摘

A systematic study of the parameter space of graphene chemical vapor deposition (CVD) on polycrystalline Cu foils is presented, aiming at a more fundamental process rationale in particular regarding the choice of carbon precursor and mitigation of Cu sublimation. CH₄ as precursor requires H₂ dilution and temperatures 鈮?000 掳C to keep the Cu surface reduced and yield a high-quality, complete monolayer graphene coverage. The H₂ atmosphere etches as-grown graphene; hence, maintaining a balanced CH₄/H₂ ratio is critical. Such balance is more easily achieved at low-pressure conditions, at which however Cu sublimation reaches deleterious levels. In contrast, C₆H₆ as precursor requires no reactive diluent and consistently gives similar graphene quality at 100鈥?50 掳C lower temperatures. The lower process temperature and more robust processing conditions allow the problem of Cu sublimation to be effectively addressed. Graphene formation is not inherently self-limited to a monolayer for any of the precursors. Rather, the higher the supplied carbon chemical potential, the higher the likelihood of film inhomogeneity and primary and secondary multilayer graphene nucleation. For the latter, domain boundaries of the inherently polycrystalline CVD graphene offer pathways for a continued carbon supply to the catalyst. Graphene formation is significantly affected by the Cu crystallography; i.e., the evolution of microstructure and texture of the catalyst template form an integral part of the CVD process.